Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * Generic pidhash and scalable, time-bounded PID allocator | |
3 | * | |
6d49e352 NYC |
4 | * (C) 2002-2003 Nadia Yvette Chambers, IBM |
5 | * (C) 2004 Nadia Yvette Chambers, Oracle | |
1da177e4 LT |
6 | * (C) 2002-2004 Ingo Molnar, Red Hat |
7 | * | |
8 | * pid-structures are backing objects for tasks sharing a given ID to chain | |
9 | * against. There is very little to them aside from hashing them and | |
10 | * parking tasks using given ID's on a list. | |
11 | * | |
12 | * The hash is always changed with the tasklist_lock write-acquired, | |
13 | * and the hash is only accessed with the tasklist_lock at least | |
14 | * read-acquired, so there's no additional SMP locking needed here. | |
15 | * | |
16 | * We have a list of bitmap pages, which bitmaps represent the PID space. | |
17 | * Allocating and freeing PIDs is completely lockless. The worst-case | |
18 | * allocation scenario when all but one out of 1 million PIDs possible are | |
19 | * allocated already: the scanning of 32 list entries and at most PAGE_SIZE | |
20 | * bytes. The typical fastpath is a single successful setbit. Freeing is O(1). | |
30e49c26 PE |
21 | * |
22 | * Pid namespaces: | |
23 | * (C) 2007 Pavel Emelyanov <xemul@openvz.org>, OpenVZ, SWsoft Inc. | |
24 | * (C) 2007 Sukadev Bhattiprolu <sukadev@us.ibm.com>, IBM | |
25 | * Many thanks to Oleg Nesterov for comments and help | |
26 | * | |
1da177e4 LT |
27 | */ |
28 | ||
29 | #include <linux/mm.h> | |
9984de1a | 30 | #include <linux/export.h> |
1da177e4 LT |
31 | #include <linux/slab.h> |
32 | #include <linux/init.h> | |
82524746 | 33 | #include <linux/rculist.h> |
1da177e4 LT |
34 | #include <linux/bootmem.h> |
35 | #include <linux/hash.h> | |
61a58c6c | 36 | #include <linux/pid_namespace.h> |
820e45db | 37 | #include <linux/init_task.h> |
3eb07c8c | 38 | #include <linux/syscalls.h> |
0bb80f24 | 39 | #include <linux/proc_ns.h> |
0a01f2cc | 40 | #include <linux/proc_fs.h> |
1da177e4 | 41 | |
8ef047aa PE |
42 | #define pid_hashfn(nr, ns) \ |
43 | hash_long((unsigned long)nr + (unsigned long)ns, pidhash_shift) | |
92476d7f | 44 | static struct hlist_head *pid_hash; |
2c85f51d | 45 | static unsigned int pidhash_shift = 4; |
820e45db | 46 | struct pid init_struct_pid = INIT_STRUCT_PID; |
1da177e4 LT |
47 | |
48 | int pid_max = PID_MAX_DEFAULT; | |
1da177e4 LT |
49 | |
50 | #define RESERVED_PIDS 300 | |
51 | ||
52 | int pid_max_min = RESERVED_PIDS + 1; | |
53 | int pid_max_max = PID_MAX_LIMIT; | |
54 | ||
61a58c6c SB |
55 | static inline int mk_pid(struct pid_namespace *pid_ns, |
56 | struct pidmap *map, int off) | |
3fbc9648 | 57 | { |
61a58c6c | 58 | return (map - pid_ns->pidmap)*BITS_PER_PAGE + off; |
3fbc9648 SB |
59 | } |
60 | ||
1da177e4 LT |
61 | #define find_next_offset(map, off) \ |
62 | find_next_zero_bit((map)->page, BITS_PER_PAGE, off) | |
63 | ||
64 | /* | |
65 | * PID-map pages start out as NULL, they get allocated upon | |
66 | * first use and are never deallocated. This way a low pid_max | |
67 | * value does not cause lots of bitmaps to be allocated, but | |
68 | * the scheme scales to up to 4 million PIDs, runtime. | |
69 | */ | |
61a58c6c | 70 | struct pid_namespace init_pid_ns = { |
9a575a92 CLG |
71 | .kref = { |
72 | .refcount = ATOMIC_INIT(2), | |
73 | }, | |
3fbc9648 SB |
74 | .pidmap = { |
75 | [ 0 ... PIDMAP_ENTRIES-1] = { ATOMIC_INIT(BITS_PER_PAGE), NULL } | |
76 | }, | |
84d73786 | 77 | .last_pid = 0, |
8f75af44 | 78 | .nr_hashed = PIDNS_HASH_ADDING, |
faacbfd3 PE |
79 | .level = 0, |
80 | .child_reaper = &init_task, | |
49f4d8b9 | 81 | .user_ns = &init_user_ns, |
435d5f4b | 82 | .ns.inum = PROC_PID_INIT_INO, |
33c42940 AV |
83 | #ifdef CONFIG_PID_NS |
84 | .ns.ops = &pidns_operations, | |
85 | #endif | |
3fbc9648 | 86 | }; |
198fe21b | 87 | EXPORT_SYMBOL_GPL(init_pid_ns); |
1da177e4 | 88 | |
92476d7f EB |
89 | /* |
90 | * Note: disable interrupts while the pidmap_lock is held as an | |
91 | * interrupt might come in and do read_lock(&tasklist_lock). | |
92 | * | |
93 | * If we don't disable interrupts there is a nasty deadlock between | |
94 | * detach_pid()->free_pid() and another cpu that does | |
95 | * spin_lock(&pidmap_lock) followed by an interrupt routine that does | |
96 | * read_lock(&tasklist_lock); | |
97 | * | |
98 | * After we clean up the tasklist_lock and know there are no | |
99 | * irq handlers that take it we can leave the interrupts enabled. | |
100 | * For now it is easier to be safe than to prove it can't happen. | |
101 | */ | |
3fbc9648 | 102 | |
1da177e4 LT |
103 | static __cacheline_aligned_in_smp DEFINE_SPINLOCK(pidmap_lock); |
104 | ||
b7127aa4 | 105 | static void free_pidmap(struct upid *upid) |
1da177e4 | 106 | { |
b7127aa4 ON |
107 | int nr = upid->nr; |
108 | struct pidmap *map = upid->ns->pidmap + nr / BITS_PER_PAGE; | |
109 | int offset = nr & BITS_PER_PAGE_MASK; | |
1da177e4 LT |
110 | |
111 | clear_bit(offset, map->page); | |
112 | atomic_inc(&map->nr_free); | |
113 | } | |
114 | ||
5fdee8c4 S |
115 | /* |
116 | * If we started walking pids at 'base', is 'a' seen before 'b'? | |
117 | */ | |
118 | static int pid_before(int base, int a, int b) | |
119 | { | |
120 | /* | |
121 | * This is the same as saying | |
122 | * | |
123 | * (a - base + MAXUINT) % MAXUINT < (b - base + MAXUINT) % MAXUINT | |
124 | * and that mapping orders 'a' and 'b' with respect to 'base'. | |
125 | */ | |
126 | return (unsigned)(a - base) < (unsigned)(b - base); | |
127 | } | |
128 | ||
129 | /* | |
b8f566b0 PE |
130 | * We might be racing with someone else trying to set pid_ns->last_pid |
131 | * at the pid allocation time (there's also a sysctl for this, but racing | |
132 | * with this one is OK, see comment in kernel/pid_namespace.c about it). | |
5fdee8c4 S |
133 | * We want the winner to have the "later" value, because if the |
134 | * "earlier" value prevails, then a pid may get reused immediately. | |
135 | * | |
136 | * Since pids rollover, it is not sufficient to just pick the bigger | |
137 | * value. We have to consider where we started counting from. | |
138 | * | |
139 | * 'base' is the value of pid_ns->last_pid that we observed when | |
140 | * we started looking for a pid. | |
141 | * | |
142 | * 'pid' is the pid that we eventually found. | |
143 | */ | |
144 | static void set_last_pid(struct pid_namespace *pid_ns, int base, int pid) | |
145 | { | |
146 | int prev; | |
147 | int last_write = base; | |
148 | do { | |
149 | prev = last_write; | |
150 | last_write = cmpxchg(&pid_ns->last_pid, prev, pid); | |
151 | } while ((prev != last_write) && (pid_before(base, last_write, pid))); | |
152 | } | |
153 | ||
61a58c6c | 154 | static int alloc_pidmap(struct pid_namespace *pid_ns) |
1da177e4 | 155 | { |
61a58c6c | 156 | int i, offset, max_scan, pid, last = pid_ns->last_pid; |
6a1f3b84 | 157 | struct pidmap *map; |
1da177e4 LT |
158 | |
159 | pid = last + 1; | |
160 | if (pid >= pid_max) | |
161 | pid = RESERVED_PIDS; | |
162 | offset = pid & BITS_PER_PAGE_MASK; | |
61a58c6c | 163 | map = &pid_ns->pidmap[pid/BITS_PER_PAGE]; |
c52b0b91 ON |
164 | /* |
165 | * If last_pid points into the middle of the map->page we | |
166 | * want to scan this bitmap block twice, the second time | |
167 | * we start with offset == 0 (or RESERVED_PIDS). | |
168 | */ | |
169 | max_scan = DIV_ROUND_UP(pid_max, BITS_PER_PAGE) - !offset; | |
1da177e4 LT |
170 | for (i = 0; i <= max_scan; ++i) { |
171 | if (unlikely(!map->page)) { | |
3fbc9648 | 172 | void *page = kzalloc(PAGE_SIZE, GFP_KERNEL); |
1da177e4 LT |
173 | /* |
174 | * Free the page if someone raced with us | |
175 | * installing it: | |
176 | */ | |
92476d7f | 177 | spin_lock_irq(&pidmap_lock); |
7be6d991 | 178 | if (!map->page) { |
3fbc9648 | 179 | map->page = page; |
7be6d991 AGR |
180 | page = NULL; |
181 | } | |
92476d7f | 182 | spin_unlock_irq(&pidmap_lock); |
7be6d991 | 183 | kfree(page); |
1da177e4 | 184 | if (unlikely(!map->page)) |
35f71bc0 | 185 | return -ENOMEM; |
1da177e4 LT |
186 | } |
187 | if (likely(atomic_read(&map->nr_free))) { | |
8db049b3 | 188 | for ( ; ; ) { |
1da177e4 LT |
189 | if (!test_and_set_bit(offset, map->page)) { |
190 | atomic_dec(&map->nr_free); | |
5fdee8c4 | 191 | set_last_pid(pid_ns, last, pid); |
1da177e4 LT |
192 | return pid; |
193 | } | |
194 | offset = find_next_offset(map, offset); | |
8db049b3 RC |
195 | if (offset >= BITS_PER_PAGE) |
196 | break; | |
61a58c6c | 197 | pid = mk_pid(pid_ns, map, offset); |
8db049b3 RC |
198 | if (pid >= pid_max) |
199 | break; | |
200 | } | |
1da177e4 | 201 | } |
61a58c6c | 202 | if (map < &pid_ns->pidmap[(pid_max-1)/BITS_PER_PAGE]) { |
1da177e4 LT |
203 | ++map; |
204 | offset = 0; | |
205 | } else { | |
61a58c6c | 206 | map = &pid_ns->pidmap[0]; |
1da177e4 LT |
207 | offset = RESERVED_PIDS; |
208 | if (unlikely(last == offset)) | |
209 | break; | |
210 | } | |
61a58c6c | 211 | pid = mk_pid(pid_ns, map, offset); |
1da177e4 | 212 | } |
35f71bc0 | 213 | return -EAGAIN; |
1da177e4 LT |
214 | } |
215 | ||
c78193e9 | 216 | int next_pidmap(struct pid_namespace *pid_ns, unsigned int last) |
0804ef4b EB |
217 | { |
218 | int offset; | |
f40f50d3 | 219 | struct pidmap *map, *end; |
0804ef4b | 220 | |
c78193e9 LT |
221 | if (last >= PID_MAX_LIMIT) |
222 | return -1; | |
223 | ||
0804ef4b | 224 | offset = (last + 1) & BITS_PER_PAGE_MASK; |
61a58c6c SB |
225 | map = &pid_ns->pidmap[(last + 1)/BITS_PER_PAGE]; |
226 | end = &pid_ns->pidmap[PIDMAP_ENTRIES]; | |
f40f50d3 | 227 | for (; map < end; map++, offset = 0) { |
0804ef4b EB |
228 | if (unlikely(!map->page)) |
229 | continue; | |
230 | offset = find_next_bit((map)->page, BITS_PER_PAGE, offset); | |
231 | if (offset < BITS_PER_PAGE) | |
61a58c6c | 232 | return mk_pid(pid_ns, map, offset); |
0804ef4b EB |
233 | } |
234 | return -1; | |
235 | } | |
236 | ||
7ad5b3a5 | 237 | void put_pid(struct pid *pid) |
92476d7f | 238 | { |
baf8f0f8 PE |
239 | struct pid_namespace *ns; |
240 | ||
92476d7f EB |
241 | if (!pid) |
242 | return; | |
baf8f0f8 | 243 | |
8ef047aa | 244 | ns = pid->numbers[pid->level].ns; |
92476d7f | 245 | if ((atomic_read(&pid->count) == 1) || |
8ef047aa | 246 | atomic_dec_and_test(&pid->count)) { |
baf8f0f8 | 247 | kmem_cache_free(ns->pid_cachep, pid); |
b461cc03 | 248 | put_pid_ns(ns); |
8ef047aa | 249 | } |
92476d7f | 250 | } |
bbf73147 | 251 | EXPORT_SYMBOL_GPL(put_pid); |
92476d7f EB |
252 | |
253 | static void delayed_put_pid(struct rcu_head *rhp) | |
254 | { | |
255 | struct pid *pid = container_of(rhp, struct pid, rcu); | |
256 | put_pid(pid); | |
257 | } | |
258 | ||
7ad5b3a5 | 259 | void free_pid(struct pid *pid) |
92476d7f EB |
260 | { |
261 | /* We can be called with write_lock_irq(&tasklist_lock) held */ | |
8ef047aa | 262 | int i; |
92476d7f EB |
263 | unsigned long flags; |
264 | ||
265 | spin_lock_irqsave(&pidmap_lock, flags); | |
0a01f2cc EB |
266 | for (i = 0; i <= pid->level; i++) { |
267 | struct upid *upid = pid->numbers + i; | |
af4b8a83 | 268 | struct pid_namespace *ns = upid->ns; |
0a01f2cc | 269 | hlist_del_rcu(&upid->pid_chain); |
af4b8a83 | 270 | switch(--ns->nr_hashed) { |
a6064885 | 271 | case 2: |
af4b8a83 EB |
272 | case 1: |
273 | /* When all that is left in the pid namespace | |
274 | * is the reaper wake up the reaper. The reaper | |
275 | * may be sleeping in zap_pid_ns_processes(). | |
276 | */ | |
277 | wake_up_process(ns->child_reaper); | |
278 | break; | |
314a8ad0 ON |
279 | case PIDNS_HASH_ADDING: |
280 | /* Handle a fork failure of the first process */ | |
281 | WARN_ON(ns->child_reaper); | |
282 | ns->nr_hashed = 0; | |
283 | /* fall through */ | |
af4b8a83 | 284 | case 0: |
af4b8a83 EB |
285 | schedule_work(&ns->proc_work); |
286 | break; | |
5e1182de | 287 | } |
0a01f2cc | 288 | } |
92476d7f EB |
289 | spin_unlock_irqrestore(&pidmap_lock, flags); |
290 | ||
8ef047aa | 291 | for (i = 0; i <= pid->level; i++) |
b7127aa4 | 292 | free_pidmap(pid->numbers + i); |
8ef047aa | 293 | |
92476d7f EB |
294 | call_rcu(&pid->rcu, delayed_put_pid); |
295 | } | |
296 | ||
8ef047aa | 297 | struct pid *alloc_pid(struct pid_namespace *ns) |
92476d7f EB |
298 | { |
299 | struct pid *pid; | |
300 | enum pid_type type; | |
8ef047aa PE |
301 | int i, nr; |
302 | struct pid_namespace *tmp; | |
198fe21b | 303 | struct upid *upid; |
35f71bc0 | 304 | int retval = -ENOMEM; |
92476d7f | 305 | |
baf8f0f8 | 306 | pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL); |
92476d7f | 307 | if (!pid) |
35f71bc0 | 308 | return ERR_PTR(retval); |
92476d7f | 309 | |
8ef047aa | 310 | tmp = ns; |
0a01f2cc | 311 | pid->level = ns->level; |
8ef047aa PE |
312 | for (i = ns->level; i >= 0; i--) { |
313 | nr = alloc_pidmap(tmp); | |
287980e4 | 314 | if (nr < 0) { |
35f71bc0 | 315 | retval = nr; |
8ef047aa | 316 | goto out_free; |
35f71bc0 | 317 | } |
92476d7f | 318 | |
8ef047aa PE |
319 | pid->numbers[i].nr = nr; |
320 | pid->numbers[i].ns = tmp; | |
321 | tmp = tmp->parent; | |
322 | } | |
323 | ||
0a01f2cc EB |
324 | if (unlikely(is_child_reaper(pid))) { |
325 | if (pid_ns_prepare_proc(ns)) | |
326 | goto out_free; | |
327 | } | |
328 | ||
b461cc03 | 329 | get_pid_ns(ns); |
92476d7f | 330 | atomic_set(&pid->count, 1); |
92476d7f EB |
331 | for (type = 0; type < PIDTYPE_MAX; ++type) |
332 | INIT_HLIST_HEAD(&pid->tasks[type]); | |
333 | ||
417e3152 | 334 | upid = pid->numbers + ns->level; |
92476d7f | 335 | spin_lock_irq(&pidmap_lock); |
c876ad76 | 336 | if (!(ns->nr_hashed & PIDNS_HASH_ADDING)) |
5e1182de | 337 | goto out_unlock; |
0a01f2cc | 338 | for ( ; upid >= pid->numbers; --upid) { |
198fe21b PE |
339 | hlist_add_head_rcu(&upid->pid_chain, |
340 | &pid_hash[pid_hashfn(upid->nr, upid->ns)]); | |
0a01f2cc EB |
341 | upid->ns->nr_hashed++; |
342 | } | |
92476d7f EB |
343 | spin_unlock_irq(&pidmap_lock); |
344 | ||
92476d7f EB |
345 | return pid; |
346 | ||
5e1182de | 347 | out_unlock: |
6e666884 | 348 | spin_unlock_irq(&pidmap_lock); |
24c037eb ON |
349 | put_pid_ns(ns); |
350 | ||
92476d7f | 351 | out_free: |
b7127aa4 ON |
352 | while (++i <= ns->level) |
353 | free_pidmap(pid->numbers + i); | |
8ef047aa | 354 | |
baf8f0f8 | 355 | kmem_cache_free(ns->pid_cachep, pid); |
35f71bc0 | 356 | return ERR_PTR(retval); |
92476d7f EB |
357 | } |
358 | ||
c876ad76 EB |
359 | void disable_pid_allocation(struct pid_namespace *ns) |
360 | { | |
361 | spin_lock_irq(&pidmap_lock); | |
362 | ns->nr_hashed &= ~PIDNS_HASH_ADDING; | |
363 | spin_unlock_irq(&pidmap_lock); | |
364 | } | |
365 | ||
7ad5b3a5 | 366 | struct pid *find_pid_ns(int nr, struct pid_namespace *ns) |
1da177e4 | 367 | { |
198fe21b PE |
368 | struct upid *pnr; |
369 | ||
b67bfe0d | 370 | hlist_for_each_entry_rcu(pnr, |
198fe21b PE |
371 | &pid_hash[pid_hashfn(nr, ns)], pid_chain) |
372 | if (pnr->nr == nr && pnr->ns == ns) | |
373 | return container_of(pnr, struct pid, | |
374 | numbers[ns->level]); | |
1da177e4 | 375 | |
1da177e4 LT |
376 | return NULL; |
377 | } | |
198fe21b | 378 | EXPORT_SYMBOL_GPL(find_pid_ns); |
1da177e4 | 379 | |
8990571e PE |
380 | struct pid *find_vpid(int nr) |
381 | { | |
17cf22c3 | 382 | return find_pid_ns(nr, task_active_pid_ns(current)); |
8990571e PE |
383 | } |
384 | EXPORT_SYMBOL_GPL(find_vpid); | |
385 | ||
e713d0da SB |
386 | /* |
387 | * attach_pid() must be called with the tasklist_lock write-held. | |
388 | */ | |
81907739 | 389 | void attach_pid(struct task_struct *task, enum pid_type type) |
1da177e4 | 390 | { |
81907739 ON |
391 | struct pid_link *link = &task->pids[type]; |
392 | hlist_add_head_rcu(&link->node, &link->pid->tasks[type]); | |
1da177e4 LT |
393 | } |
394 | ||
24336eae ON |
395 | static void __change_pid(struct task_struct *task, enum pid_type type, |
396 | struct pid *new) | |
1da177e4 | 397 | { |
92476d7f EB |
398 | struct pid_link *link; |
399 | struct pid *pid; | |
400 | int tmp; | |
1da177e4 | 401 | |
92476d7f EB |
402 | link = &task->pids[type]; |
403 | pid = link->pid; | |
1da177e4 | 404 | |
92476d7f | 405 | hlist_del_rcu(&link->node); |
24336eae | 406 | link->pid = new; |
1da177e4 | 407 | |
92476d7f EB |
408 | for (tmp = PIDTYPE_MAX; --tmp >= 0; ) |
409 | if (!hlist_empty(&pid->tasks[tmp])) | |
410 | return; | |
1da177e4 | 411 | |
92476d7f | 412 | free_pid(pid); |
1da177e4 LT |
413 | } |
414 | ||
24336eae ON |
415 | void detach_pid(struct task_struct *task, enum pid_type type) |
416 | { | |
417 | __change_pid(task, type, NULL); | |
418 | } | |
419 | ||
420 | void change_pid(struct task_struct *task, enum pid_type type, | |
421 | struct pid *pid) | |
422 | { | |
423 | __change_pid(task, type, pid); | |
81907739 | 424 | attach_pid(task, type); |
24336eae ON |
425 | } |
426 | ||
c18258c6 | 427 | /* transfer_pid is an optimization of attach_pid(new), detach_pid(old) */ |
7ad5b3a5 | 428 | void transfer_pid(struct task_struct *old, struct task_struct *new, |
c18258c6 EB |
429 | enum pid_type type) |
430 | { | |
431 | new->pids[type].pid = old->pids[type].pid; | |
432 | hlist_replace_rcu(&old->pids[type].node, &new->pids[type].node); | |
c18258c6 EB |
433 | } |
434 | ||
7ad5b3a5 | 435 | struct task_struct *pid_task(struct pid *pid, enum pid_type type) |
1da177e4 | 436 | { |
92476d7f EB |
437 | struct task_struct *result = NULL; |
438 | if (pid) { | |
439 | struct hlist_node *first; | |
67bdbffd | 440 | first = rcu_dereference_check(hlist_first_rcu(&pid->tasks[type]), |
db1466b3 | 441 | lockdep_tasklist_lock_is_held()); |
92476d7f EB |
442 | if (first) |
443 | result = hlist_entry(first, struct task_struct, pids[(type)].node); | |
444 | } | |
445 | return result; | |
446 | } | |
eccba068 | 447 | EXPORT_SYMBOL(pid_task); |
1da177e4 | 448 | |
92476d7f | 449 | /* |
9728e5d6 | 450 | * Must be called under rcu_read_lock(). |
92476d7f | 451 | */ |
17f98dcf | 452 | struct task_struct *find_task_by_pid_ns(pid_t nr, struct pid_namespace *ns) |
92476d7f | 453 | { |
f78f5b90 PM |
454 | RCU_LOCKDEP_WARN(!rcu_read_lock_held(), |
455 | "find_task_by_pid_ns() needs rcu_read_lock() protection"); | |
17f98dcf | 456 | return pid_task(find_pid_ns(nr, ns), PIDTYPE_PID); |
92476d7f | 457 | } |
1da177e4 | 458 | |
228ebcbe PE |
459 | struct task_struct *find_task_by_vpid(pid_t vnr) |
460 | { | |
17cf22c3 | 461 | return find_task_by_pid_ns(vnr, task_active_pid_ns(current)); |
228ebcbe | 462 | } |
228ebcbe | 463 | |
1a657f78 ON |
464 | struct pid *get_task_pid(struct task_struct *task, enum pid_type type) |
465 | { | |
466 | struct pid *pid; | |
467 | rcu_read_lock(); | |
2ae448ef ON |
468 | if (type != PIDTYPE_PID) |
469 | task = task->group_leader; | |
81b1a832 | 470 | pid = get_pid(rcu_dereference(task->pids[type].pid)); |
1a657f78 ON |
471 | rcu_read_unlock(); |
472 | return pid; | |
473 | } | |
77c100c8 | 474 | EXPORT_SYMBOL_GPL(get_task_pid); |
1a657f78 | 475 | |
7ad5b3a5 | 476 | struct task_struct *get_pid_task(struct pid *pid, enum pid_type type) |
92476d7f EB |
477 | { |
478 | struct task_struct *result; | |
479 | rcu_read_lock(); | |
480 | result = pid_task(pid, type); | |
481 | if (result) | |
482 | get_task_struct(result); | |
483 | rcu_read_unlock(); | |
484 | return result; | |
1da177e4 | 485 | } |
77c100c8 | 486 | EXPORT_SYMBOL_GPL(get_pid_task); |
1da177e4 | 487 | |
92476d7f | 488 | struct pid *find_get_pid(pid_t nr) |
1da177e4 LT |
489 | { |
490 | struct pid *pid; | |
491 | ||
92476d7f | 492 | rcu_read_lock(); |
198fe21b | 493 | pid = get_pid(find_vpid(nr)); |
92476d7f | 494 | rcu_read_unlock(); |
1da177e4 | 495 | |
92476d7f | 496 | return pid; |
1da177e4 | 497 | } |
339caf2a | 498 | EXPORT_SYMBOL_GPL(find_get_pid); |
1da177e4 | 499 | |
7af57294 PE |
500 | pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns) |
501 | { | |
502 | struct upid *upid; | |
503 | pid_t nr = 0; | |
504 | ||
505 | if (pid && ns->level <= pid->level) { | |
506 | upid = &pid->numbers[ns->level]; | |
507 | if (upid->ns == ns) | |
508 | nr = upid->nr; | |
509 | } | |
510 | return nr; | |
511 | } | |
4f82f457 | 512 | EXPORT_SYMBOL_GPL(pid_nr_ns); |
7af57294 | 513 | |
44c4e1b2 EB |
514 | pid_t pid_vnr(struct pid *pid) |
515 | { | |
17cf22c3 | 516 | return pid_nr_ns(pid, task_active_pid_ns(current)); |
44c4e1b2 EB |
517 | } |
518 | EXPORT_SYMBOL_GPL(pid_vnr); | |
519 | ||
52ee2dfd ON |
520 | pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type, |
521 | struct pid_namespace *ns) | |
2f2a3a46 | 522 | { |
52ee2dfd ON |
523 | pid_t nr = 0; |
524 | ||
525 | rcu_read_lock(); | |
526 | if (!ns) | |
17cf22c3 | 527 | ns = task_active_pid_ns(current); |
52ee2dfd ON |
528 | if (likely(pid_alive(task))) { |
529 | if (type != PIDTYPE_PID) | |
530 | task = task->group_leader; | |
81b1a832 | 531 | nr = pid_nr_ns(rcu_dereference(task->pids[type].pid), ns); |
52ee2dfd ON |
532 | } |
533 | rcu_read_unlock(); | |
534 | ||
535 | return nr; | |
2f2a3a46 | 536 | } |
52ee2dfd | 537 | EXPORT_SYMBOL(__task_pid_nr_ns); |
2f2a3a46 PE |
538 | |
539 | pid_t task_tgid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns) | |
540 | { | |
541 | return pid_nr_ns(task_tgid(tsk), ns); | |
542 | } | |
543 | EXPORT_SYMBOL(task_tgid_nr_ns); | |
544 | ||
61bce0f1 EB |
545 | struct pid_namespace *task_active_pid_ns(struct task_struct *tsk) |
546 | { | |
547 | return ns_of_pid(task_pid(tsk)); | |
548 | } | |
549 | EXPORT_SYMBOL_GPL(task_active_pid_ns); | |
550 | ||
0804ef4b | 551 | /* |
025dfdaf | 552 | * Used by proc to find the first pid that is greater than or equal to nr. |
0804ef4b | 553 | * |
e49859e7 | 554 | * If there is a pid at nr this function is exactly the same as find_pid_ns. |
0804ef4b | 555 | */ |
198fe21b | 556 | struct pid *find_ge_pid(int nr, struct pid_namespace *ns) |
0804ef4b EB |
557 | { |
558 | struct pid *pid; | |
559 | ||
560 | do { | |
198fe21b | 561 | pid = find_pid_ns(nr, ns); |
0804ef4b EB |
562 | if (pid) |
563 | break; | |
198fe21b | 564 | nr = next_pidmap(ns, nr); |
0804ef4b EB |
565 | } while (nr > 0); |
566 | ||
567 | return pid; | |
568 | } | |
569 | ||
1da177e4 LT |
570 | /* |
571 | * The pid hash table is scaled according to the amount of memory in the | |
572 | * machine. From a minimum of 16 slots up to 4096 slots at one gigabyte or | |
573 | * more. | |
574 | */ | |
575 | void __init pidhash_init(void) | |
576 | { | |
074b8517 | 577 | unsigned int i, pidhash_size; |
1da177e4 | 578 | |
2c85f51d JB |
579 | pid_hash = alloc_large_system_hash("PID", sizeof(*pid_hash), 0, 18, |
580 | HASH_EARLY | HASH_SMALL, | |
31fe62b9 TB |
581 | &pidhash_shift, NULL, |
582 | 0, 4096); | |
074b8517 | 583 | pidhash_size = 1U << pidhash_shift; |
1da177e4 | 584 | |
92476d7f EB |
585 | for (i = 0; i < pidhash_size; i++) |
586 | INIT_HLIST_HEAD(&pid_hash[i]); | |
1da177e4 LT |
587 | } |
588 | ||
589 | void __init pidmap_init(void) | |
590 | { | |
840d6fe7 | 591 | /* Verify no one has done anything silly: */ |
c876ad76 EB |
592 | BUILD_BUG_ON(PID_MAX_LIMIT >= PIDNS_HASH_ADDING); |
593 | ||
72680a19 HB |
594 | /* bump default and minimum pid_max based on number of cpus */ |
595 | pid_max = min(pid_max_max, max_t(int, pid_max, | |
596 | PIDS_PER_CPU_DEFAULT * num_possible_cpus())); | |
597 | pid_max_min = max_t(int, pid_max_min, | |
598 | PIDS_PER_CPU_MIN * num_possible_cpus()); | |
599 | pr_info("pid_max: default: %u minimum: %u\n", pid_max, pid_max_min); | |
600 | ||
61a58c6c | 601 | init_pid_ns.pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL); |
73b9ebfe | 602 | /* Reserve PID 0. We never call free_pidmap(0) */ |
61a58c6c SB |
603 | set_bit(0, init_pid_ns.pidmap[0].page); |
604 | atomic_dec(&init_pid_ns.pidmap[0].nr_free); | |
92476d7f | 605 | |
74bd59bb | 606 | init_pid_ns.pid_cachep = KMEM_CACHE(pid, |
5d097056 | 607 | SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_ACCOUNT); |
1da177e4 | 608 | } |